Apparatus for the controlled extrusion of multi-component synthetic resinous bodies

ABSTRACT

In extrusion of layered film where a layered stream is discharged from a single die, control of the volume of material passing through the feed ports is obtained by introducing varying mechanical shear rates to at least a portion of the individual layers of the composite stream.

United States Patent Schrenk [54] APPARATUS FOR THE CONTROLLED EXTRUSIONOF MULTI-COMPONENT SYNTHETIC RESINOUS BODIES [72] Inventor: Walter J.Schrenk, Bay City, Mich.

[73] Assignee: The Dow Chemical Company,

Midland, Mich.

[22] Filed: July 20, 1970 [21] App1.No.: 56,503

Related US. Application Data [60] Division of Ser. No. 811,275, March10, 1969,

Pat. No. 3,555,128, which is a continuation-inpart of Ser. No. 603,981,Dec. 22, 1966, abandoned.

[52] US. Cl. ..425/109, 425/131, 425/198, 425/305, 425/379 [51] Int. Cl...B29f 3/02 [58] Field of Search ..264/171, 176; 18/13 P, 2 F, 18/15 R,15 F [451 Aug. 29, 1972 [56] References Cited UNITED STATES PATENTS2,803,041 8/1957 Hill et al. ..18/13 P X 3,320,636 5/1967 Corbett......18/l3 P 3,321,804 5/1967 Breidt et al 18/1 3 P 3,346,918 10/1967Peleuze et a1 ,.l8/l3 P X 3,405,425 10/ 1968 Buckley et al ..18/13 P3,444,031 5/1969 Schrenk ..'.....18/13 P X 3,460,203 8/ 1969 Losserand..18/13 P 3,487,505 1/1970 Chisholm et al ..18/1 3 P Primary Examiner.l.Spencer Overholser Assistant ExaminerB. D. Tobor Att0rneyGriswold &Burdick, Richard G. Waterman and Robert B. Ingraham [57] ABSTRACT Inextrusion of layered film where a layered stream is discharged from asingle die, control of the volume of materialpassing through the feedports is obtained by introducing varying mechanical shear rates to atleast a portion of the individual layers of the composite stream.

4 Claims, 4 Drawing Figures APPARATUS FOR THE CONTROLLED EXTRUSION OFMULTI-COMPONENT SYNTHETIC RESINOUS BODIES This application is adivisional application of my copending application Ser. No. 811,275,filed Mar. 10, 1969, which in turn is a continuation-in-part applicationof my earlier application Ser. No. 603,981, filed Dec. 22, 1966, nowabandoned.

This invention relates to apparatus for the extrusion of multi-componentsynthetic resinous bodies, and more particularly relates to apparatusfor the extrusion of synthetic resinous multi-component bodies whereincontrol of the various components is readily achieved.

Many multi-component bodies are prepared from synthetic resinousthermoplastic materials by the simultaneous extrusion of two or moreheat plastified components in such a manner that they are combinedwithin a die or like shaping configuration in the thermoplastic stageand subsequently shaped to a desired configuration. Some of such bodiesare set forth in US. Pat. No. 3,498,873; application Ser. Nos. 445,851,filed Mar. 29, 1965 (now abandoned) and 562,220, filed July 1, 1966 (nowabandoned). Oftentimes in the preparation of multi-component bodies,such as layered film, which consist of a plurality of layers ofsynthetic resinous materials which may be in altemating or otherconfiguration, it is desirable to closely control the thickness of suchlayers, particularly when opti cal properties are desired. Generally,the optical properties are closely dependent upon layer thickness oflayer configuration. In utilizing conventional extrusion equipment,oftentimes the viscous drag exerted by the force of the extrusionapparatus; that is, in the die and various passages within the die,results in a flow pattern that is undesirable for many given materialsat a given temperature. A suitable die and passage configuration may bedeveloped to compensate for wall defects. However, in the preparation ofsuch multi-component products, it is desirable that a single piece ofequipment be employed with a variety of synthetic resinous materials andthat the temperature of such material in the heat plastified conditioncan be varied to obtain optimum conditions for each particular batch ofresin.

It would be advantageous if there were available apparatus for theextrusion of multi-component synthetic resinous plastic bodies whereinclose control of the flow of various streams of heat plastified materialwithin the extrusion apparatus can be maintained.

It would also be advantageous if there were apparatus available for theproduction of multi-component synthetic resinous articles wherein thevarious components are present as distinct and separate phases whichwould permit close control of at least one dimension of the phases.

It would also be advantageous if there were available apparatus for thepreparation of synthetic resinous film having a layered structurecomposed of alternating layers of diverse synthetic resinous materialwherein the thickness of such layers could be closely controlled.

These benefits and other advantages in accordance with the presentinvention are achieved in an apparatus for the simultaneous extrusion ofat least two diverse synthetic resinous materials into a composite body,the apparatus comprising at least a first heat plastified syntheticresinous supply means, a second heat plastified synthetic resin supplymeans adapted to deliver at least a first and a second heat plastifiedstream, means to divide the first stream and means to divide the secondstream into a plurality of substreams, means to re-combine thesubstreams in a desired relationship into a composite stream, means todeform the composite stream into a desired configuration, the im-'provement which comprises stream shearing means adapted to selectivelyapply a shearing force to at least some of the substreams and alter theflow rate thereof.

The apparatus of the present invention beneficially performs a processfor the simultaneous extrusion of at least two diverse syntheticresinous materials within a stream deforming configuration whereby atleast two streams of diverse synthetic resinous material are eachdivided into a plurality of streams and subsequently recombined into asingle main stream to form a multicomponent main stream of diverse heatplastified synthetic resinous material which is subsequently deformed toprovide a product of a desired configuration and cooled below itsthermoplastic temperature. At least a portion of the streams formed bysubdivision are subjected to varying shear rates by means of mechanicalmotion of a surface adjacent thereto to thereby provide a desireddistribution of the diverse synthetic resinous material within the mainstream.

Further features and advantages of the present invention will becomemore apparent from the following specification taken in connection withthe drawing wherein:

FIG. 1 is a schematic representation of one embodiment of an apparatusin accordance with the invention.

FIG. 2 is a sectional view of the apparatus of FIG. 1 taken along theline 22.

FIG. 3 is a detail of one of the feed slots in the apparatus of FIGS. 1and 2.

FIG. 4 depicts an alternate embodiment of the invention.

In FIG. 1 there is schematically represented an extrusion apparatus inaccordance with the present invention generally designated by thereference numeral 10. The apparatus 10 comprises in cooperativecombination an extrusion housing 11. The extrusion housing 11 defines aninternal cavity, a first polymer receiving manifold 12 and a secondpolymer receiving manifold 14. The first polymer receiving manifold 12is in operative communication with a first heat plastified syntheticresinous material supply source 16 by means of a passageway 17.Beneficially, the supply means 16 is a heat plastified screw extruder orlike apparatus. The second polymer receiving manifold 14 is in operativecommunication with a second source of heat plastified synthetic resinousmaterial 19 by means of a passageway 20 defined by the housing 11. Thehousing 11 defines a discharge cavity or passageway 22. The dischargecavity 22 has a first or entrance portion 23 and a second or dischargeportion 24. In the embodiment depicted in FIG. 1 and 2, the portions 23and 24 have a generally like configuration. The entrance portion 23terminates adjacent a feed block and the exit portion 24 terminatesadjacent a slot-like discharge or extrusion orifice 28. Thus, thedischarge cavity 22 has a double fishtail configuration wherein, inessence, two fishtails are in abutting relationship and lie in planesdisposed at from each other. The distribution block 26 separates themanifolds l2 and 14 from the discharge passageway 22 and providesselective communication therebetween. The distribution block 26 definesa plurality of passageways or slots 30 extending between the manifold 12and the discharge passageway 22. Each of the slots 30 has a discharge orterminal end 31 and an inlet end 32. lnterdigital between the slots orpassageways 30 are a plurality of slots 35. The slots 35 providecommunication between the manifold 14 and the discharge passageway 22.The passageways 35 have a discharge end 36 in communication with thepassageway 22 and inlet ends 37 in communication with the manifold 14.The discharge openings 31 and 36 of the passageways 30 and 35 arearranged generally in alternating relationship and discharge in a sideby side manner. A mechanical shear producing means 40 is disposed at theinlet opening 32 of each of the passageways 30. The shear producingmeans beneficially may constitute, as is depicted in FIG. 1, a rotatingshaft, an oscillating rod or like means to provide adjacent surfaceswhich have relative motion, i.e., continuous or continual motion, asheat plastified material is passed therebetween.

In FIG. 2 there is illustrated a view of the apparatus of FIG. 1 takenalong the line 22 thereof illustrating in further detail therelationship of the slots 30 and 35 and a particular form of shearproducing means 40. The shear producing means 40 comprises a generallycylindrical body 42 disposed adjacent and in spaced relationship to theentrance end 32 of a passageway 30. A cylindrical body 42 passes througha first opening 44 in the housing 11 and a second opening 45 definedtherein. A first rotary seal 46 and a second rotary seal 47 prevent flowof material from the manifold 12 along the body 42. A rotating means 49is integrally affixed to the body 42 and provides rotation at a desiredrate to provide continuous shear between the body 42 and the adjacentportion of the distribution block 26 defining the slots or passages 30.The rotating means 49 may be any conventional means employed to providerotary motion at a controlled rate such as an electric motor, a lineshaft with variable speed gearing and the like.

In FIG. 3 there is depicted a fragmentary view of a portion of the feedblock 26 depicting the relationship between a slot 30, the inlet end ofthe slot 32 and the shear producing means 40. The inlet portion of theslot 32 has a generally semi-circular cross-section. The shear producingmeans 40 is positioned within the entrance end 32 in such a manner thatit is asymmetrically located and rotated in the direction indicated bythe arrow causing a flow of material into the slot or passageway 30 at arate more or less proportional to the rate of rotation of the shearproducing means 40.

In operation of the apparatus as depicted in accordance with theinvention as described in FIGS. 1, 2 and 3, a first synthetic resinousheat plastified material is provided to the manifold 12 through thepassageway away from the source 16. A second source 19 provides a secondsynthetic resinous heat plastified material to the manifold 14. Thematerial from the manifold 12 is forced through the passageways 30 andis discharged as a plurality of generally parallel streams in the firstend 23 of the passageway 22. The material from the second manifold 14passes through the slots or passageways 35 and is discharged as aplurality of streams in the first end 23 of the passageway 22. Thus, thestreams from the various passageways 30 and 35 are disposed inalternating or interdigitating arrangement. The configuration of thepassageways 22 is such that rotation of the stream laminae does notoccur and the generally parallel regions of diverse polymeric materialflow toward the second end 24. As they flow toward the second end 24,the configuration of the passageway is such that their thicknessdecreases and their width increases until at the discharge opening 28 arelatively thin film or sheet is formed wherein a plurality of layersexist, all disposed generally parallel to the major surfaces of thesheet. Selective rotation of the, shearing means 40 provides close andaccurate control of the relative quantities of material discharged fromthe first manifold 12 through the various slots 30. Thus, the relativethicknesses of the layers in the resultant film are readily controlledby individually varying the rate of rotation of the shear means 40. Asindicated in FIG. 3, rotation of the shear means 40 in the directionindicated by the arrow aids flow of the polymeric material through theslot 30. As the speed of rotation is decreased toward zero, lessmaterial flows. A further decrease in the rate of flow is obtained byreversing the direction of rotation of the shear means. Similarly, ifdesired, suitable shear means may be provided for all or some of thestreams of either or both polymeric materials.

One particularly beneficial and advantageous application of theapparatus such as is depicted in FIG. 1 is in the preparation of a filmwherein alternate layers have a monotonically increasing layer thicknesssuch that where d, thickness of nth layer d =thickness of 1st layer nno. of layer a rate of layer thickness increase Employing thearrangement such as is depicted in FIGS. 1, 2 and 3, the characteristicsof a smoothly rotating roll are that the pumping rate is generallydirectly proportional to the shear or speed thereof. Assuming each shearproducing means has a like diameter, the speed of the individual rollsis W W1 an where W RPM (revolution per minute) or nth rotor W RPM of 1strotor to give sufiicient rate to make n no. of rotor In FIG. 4 there isdepicted a schematic cutaway view of an alternate embodiment of theinvention designated by the reference numeral 55. The embodiment 55comprises a housing 56 defining a first polymer inlet manifold 57. Thepolymer inlet manifold is in communication with a first heat plastifiedpolymer supply means, not shown. A second polymer supply manifold, notshown, is also defined by the housing 56. A distribution block 59 isdisposed within the housing 56. The distribution block 59 defines aplurality of slots or passageways 60 extending from the manifold 57 to adischarge passageway 62 having the general configuration of thedischarge passageway 22 of FIG. 1. The slots or passageways 60 have aninlet end 61 communicating with the manifold 57 and discharge openings63 communicating with the passageway 62. The distribution block 59defines a plurality of discharge passageways 65. The passageways 65communicate with the discharge passageway 62 and with the second polymersupply manifold, not shown. A plurality of shearing elements 67 aredisposed slidably within the housing 56. The shearing elements 76 have afirst end 68. Each shearing element 67 has a second end 69 disposedexternal to the housing 56. Each shearing element 67 is resilientlyurged from the manifold 57 by means of a shearing element retractor 71or compression spring. Each of the second ends 69 is in operativeengagement with cams 72, 72a, 72b, 72c and 72d. The cams 72 are mountedupon rotatable shafts 73, 73a, 73b 73c and 73d, respectively.

In the operation of the embodiment of the invention as depicted in FIG.4, heat plastified material is supplied to the manifold 57 and to thesecond manifold, not shown. Thermoplastic material is forced from theslots 60 and 65 to provide an interdigitating or interleaved arrangementof streams in the passageway 62. The amount of material flowing from theslots 60 is readily varied by increasing or decreasing the amount ofshear in the region of the inlet portion 61 of the passageways 60. Thisis readily accomplished by varying the reciprocating travel of the shearelement 67 which is easily controlled by a degree of eccentricity of thecams 72, 72a, 72b, 72c and 72d. Alternatively, cams of likeconfiguration may be employed and the speed of rotation of the shaftssuch as the shafts 73, 73a, 73b, 7 3c and 73d varied to give a desireddegree of shear.

Employing apparatus in accordance with the present invention such as isdepicted in FIGS. 1-4, multi-component layered films such as aredescribed in U.S. Pat. No. 3,498,873; application Ser. Nos. 445,851 (nowabandoned) and 562,220 (now abandoned) are prepared while maintaininghighly accurate control of the various layer thicknesses.

As is apparent from the foregoing specification, the present inventionis susceptible of being embodied with various alterations andmodifications which may differ particularly from those that have beendescribed in the preceding specification and description. For thisreason, it is to be fully understood that all of the foregoing isintended to be merely illustrative and is not to be construed orinterpreted as being restrictive or otherwise limiting of the presentinvention.

What is claimed is:

1. An apparatus for the simultaneous extrusion of at least two diversesynthetic resinous materials into a layered composite body, theapparatus comprising a first heat plastified synthetic resinous materialsupply means adapted to deliver a first heat plastified stream,

a second heat plastified synthetic resinous material supply meansadapted to deliver a second heat plastified stream,

means to divide the first stream and means to divide the second streaminto a plurality of substreams each means having an entrance and anexit,

means to recombine the substreams in a desired relationship into acomposite layered stream,

means to deform the composite layered stream into a desiredconfiguration, the improvement which comprises stream shearing means forselectively applying a shearing force, by continual mechanical motion ofa surface of said stream shearing means in contact with a stream,

wherein the stream shearing means comprises at least one moveable bodypositioned adjacent to, and in spaced relationship to the entrance of adividing means.

2. The apparatus of claim 1 wherein the means to selectively apply ashearing force comprises at least one rotating element.

3. The apparatus of claim 1 wherein the means to selectively apply ashearing force is a reciprocating element.

4. The apparatus of claim 1 wherein the means to deform the compositestream into a desired configuration comprises a housing defining apassageway, the passageway having an entrance portion and a dischargeportion, the entrance and discharge portions being of elongatecross-sectional configuration and the cross-sectional configurationslying in planes generally normal to the axis of the passageway, thelongitudinal axis of the entrance and discharge cross-sectionalconfigurations being disposed in planes generally normal to each otherand containing a longitudinal axis of the passageway.

1. An apparatus for the simultaneous extrusion of at least two diversesynthetic resinous materials into a layered composite body, theapparatus comprising a first heat plastified synthetic resinous materialsupply means adapted to deliver a first heat plastified stream, a secondheat plastified synthetic resinous material supply means adapted todeliver a second heat plastified stream, means to divide the firststream and means to divide the second stream into a plurality ofsubstreams, each means having an entrance and an exit, means torecombine the substreams in a desired relationship into a compositelayered stream, means to deform the composite layered stream into adesired configuration, the improvement which comprises stream shearingmeans for selectively applying a shearing force, by continual mechanicalmotion of a surface of said stream shearing means in contact with astream, wherein the stream shearing means comprises at least onemoveable body positioned adjacent to, and in spaced relationship to theentrance of a dividing means.
 2. The apparatus of claim 1 wherein themeans to selectively apply a shearing force comprises at least onerotating element.
 3. The apparatus of claim 1 wherein the means toselectively apply a shearing force is a reciprocating element.
 4. Theapparatus of claim 1 wherein the means to deform the composite streaminto a desired configuration comprises a housing defining a passageway,the passageway having an entrance portion and a discharge portion, theentrance and discharge portions being of elongate cross-sectionalconfiguration and the cross-sectional configurations lying in planesgenerally normal to the axis of the passageway, the longitudinal axis ofthe entrance and discharge cross-sectional configurations being disposedin planes generally normal to each other and containing a longitudinalaxis of the passageway.